What if all of the Sunbeam sun's output of visible light were bundled up into a laser-like beam that had a diameter of around 1m once it reaches Earth?

If you were standing in the path of the beam, you would obviously die pretty quickly. You wouldn't really die of anything, in the traditional sense. You would just stop being biology and start being physics.

When air heats up, the electrons are stripped away from their atoms, turning it to plasma. The ongoing flood of radiation from the beam has to pass through this plasma, so we need to know how transparent plasma is to different kinds of light. At this point, I'd like to mention the 1964 paper Opacity Calculations: Past and Future, by Harris L. Mayer, which contains the single best opening paragraph to a physics paper I've ever seen:

Initial steps for this symposium began a few billion years ago. As soon as the stars were formed, opacities became one of the basic subjects determining the structure of the physical world in which we live. And more recently with the development of nuclear weapons operating at temperatures of stellar interiors, opacities become as well one of the basic subjects determining the processes by which we may all die.

Compared to air, the plasma is relatively transparent to x-rays. The x-rays would pass through the plasma, heating it through effects called Compton scattering and pair production, but would be stopped quickly when they reached the non-plasma air outside the bubble. However, the steady flow of x-rays from the growing pocket of superhot air closer to the beam would turn a steadily-growing bubble of air to plasma. The fresh plasma at the edge of the bubble would give off infrared radiation, which would head out toward the horizon (along with the infrared already on the way), heating whatever it finds there.

Max's scenario may have doomed Earth, but if it's any consolation, we wouldn't necessarily die alone.